Resistance control device



Jan. 7, 1930., G. `LMEUER ET AL.

RESISTANCE CONTROL DEVICE y Filedovot, 5, 1925 Si l lgfz/ENroRs.I l,Mlm/m GSV/wem,

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PUNITED STATES PATENT v4orf-1:2151

@maar 3.1mm um wmnun O. STEVENS, Ol' HILWAUKEE, WISCONSIN, ABSIGNOBS, BYim .LBBIGNIENT TO OUTLEB-HAHHER, INC., A CORPORATION OIvDELA..

waterman connor.. 'nnvron Application. led October 5, 1985. Serial No.00,391.

This invention relates to improvements in resistance control devices ofthe type -employed in radio and similar aparatus.

An object of the invention is to provide a resistance control device ofsimple and durable construction l Another object is to facilitateassembly of the several elements of the device.

Another object is to provide interchangeable elements whereby theelectrical characteristics of the device may be altered as desired.

Another objectv is to provide novel means for removably securing, thedevice to a panel or other sup ort. v

Another object is to provide improved supporting and securing means forthe resistance elements of devices of this character.

Other objects and advantages of the invention will hereinafter ap ear.

In the accompanyin rawin wherein are illustrated certain of t 1e emboents which the'invention may assume in practice,

Figure 1 is a vertical 'sectional .view of a radio rheostat constructedin accordance with my'invention;

Fig. 2 is a rear elevational view of the device shown in Fig. 1; y

Fig. 3 is a vertical sectional view of a modiiiedform of-the deviceillustrated in Fig. 1, whereby the same is adapted for use as apotentiometer;

Fig. 4 is a rear elevational view of the device shown in Fig. 3; and,

Fig. 5 is a sectional view on the line 5-5 of Fig. 3.

Re erring to Fi 1 and 2 of the drawin the numeral 10 signatesa metallichu member havin a reduced end portion 11 of a size correspon 'ng to thesize of opening 12 in a metallic member 13. The member 13 abuts ashoulder 14-on hub member 10, and the end portion 11 of the latter isadapted to be spun' or riveted over the member 13, as indicated at 15,to secure said arts against relative movement. Huby member 10 `isinternally vscrew-threaded, as indicated at 16,v

' to receive an externally screw-threaded cooperative clamping member 17The membersv 1n centering the same within the perforation,

and also to insure a proper clamping action of said members.

Rotatabl mounted upon the hub member 10 is a su stantially cylindricalinsulating base member 21, the latter having an annular projectingportion 22 (Figs. 1 and 5), which is provided with a groove 23. Groove23 is concentrically disposed within the annular 'po'lecting portion 22,whereas the continuity e former is interrupted as indicated-at 24 toprovide abutments 25 and 26 for engagement with a stationary projection27 upon the member 13. Rotary lmovement ofbase member 21 is thus limitedfor a purpose hereinafter set forth.

The base member 21 is also provided with a peripheral cut-away portion28 to receive the resistance element 29, the annular shoulder 30 beingadapted to definitely position said element with respect to the base. Asshown, said resistance element comprises a flexible strip of insulatingmaterial' 31 around which a suitable number of turns of relatively newire 32 are Wound in closely adjacent relationship to each other. Each.end of the wire 32 is'preferabl threaded one or more -times through'suita le openings 33 and 34 near the respective ends of the strip toprevent slippage or unwinding of the wire, whereas one end thereof leadsoil from the wound portion as indicated in dotted lines at '35 (Fig.2).I

The rear face of base member 21 is provided' with a notch or recess 36to receive a .substantially U-,shaped metallic member 37 the reduced endportions 38 and 39 of the latter being adapted to pass throughcorresponding openings in the ends offlexible strip 31,"whereas saidends 38 Aand 39 are thereafter bent, as shown in Fig. 2, to hold theends of'said strip in the desired position. In practice the arms of theU-shaped member 37 are preferably brought suiiciently close together toprovide a slightly reduced circumference of the completed resistanceelement whereby the latter is required to be sprung over'the cut-awayportion 28 of thel 42 of a disk-shaped member 43. Member 43 is providedwith a central opening 44 and a pair of tongues or projections 45adapted to take within a corresponding slot 46 in the reduced end 47 ofa tubular member 48. Wire 35 is adapted to be laid in 'slot 46, and thesame is clamped therein by said tongues 45,

Vthe reduced end 47 being thereafter riveted or bent over the member 43,as indicated at 49', to hold said parts together, with the springfingers 42 compressed. The'member 43 therefore tends to draw the member48 backwardly, but such movement is limited by y engagement of ashoulder 50 on the latter with the annular internal flange 51 on hubmember '10. Moreover, this arrangement insures positive electricalengagement between member 48 and hub member 10. Member 48 is freelyrotatable within the member 17, whereas the former is provided with ascrewthreaded portion 52 for engagement by a correspondingly threadedinsert 53 in a molded knob or handle '54.` A pointer or indicator 55is'also preferably threaded onto portion 52 prior to the knob 54,whereby said polnter and knob may act as lock nuts with respect to eachother to bind or lock the same to member 48.' It will thus be seen thatrotary move? ment of knob 54 in one direction or the other will effectcorresponding movement of theresistance element 29, due totheinterlocking connections .aforedescribed The member 13 is provided withan enlarged rearwardly bent portion 56 of arcshape, said member beingperforated as indl- A cated at 57 to facilitate such bending thereof.

The arc-shaped portion 56 is. provlded with a plurality of rforations58, 59 and 60, whereas `each 0in-)said openings is provided with aninsulating lining by means of the annular in-bent flanges 61 on aninsulating strip 62, as clearly shown in Fig. 1. A screw 63 passesupwardlythrough insulated opening 60, and a washer 64 of brass or otherconducting material is placed thereover. A nut 65 1s threaded ontosaid'screw to hold the same in position. As will be apparent the screw63 is in electrical] conductive relation to portion 56 of memb r 13.Screw 63 is therefore adapted to serve as one of the circuit terminals,a nut 66 being provided for clamping the circuit wire thereto.

A screw 67 passes through the insulated opening 58 at the opposite endof portion 56, said screw being in electrical contact with and adaptedto support an elongated contact member 68. An insulating washer 69 isplaced over' the upper end of screw 67 and the several parts are heldinposition by the nut 70. It will thus be seen that screw 67 is completelyinsulated from portion 56 of member 13. A nut 71 is adapted to providefor con- -nection of the otherfwire of the circuit. The

intermediate opening 59 in portion 56 is not utilized Iin thearrangement illustrated in Figs. l and 2,'-the'same beiner adapted tofacilitate the circuit connections lllustrated yin Figs. 3, 4 and 5 ashereinafter described.

Contact member 68 is preferably provided with a relativelyl narrowinward projectlon or rib 72 for engagement with the coils of resistancewire 32. `The liexible strip 31 is also preferably provided with a bossorprojection 7 3 for engagement with rib 72, asshown, to insuredisengagement of the latter'from wire v32 when the parts are in theposition ill'ustrated in Fig. 2. In said position circuit isinterrupted, whereas upon turning of knob 54 in a clockwise directioncircuit is completed, to first include all of the resistance and thengradually exclude the same upon continued clockwise movement of saidknob.,

Such clockwise movement of the knob and its associated elements islimited by engagement of the shoulder 25 with projection 27 (shown indotted lines in Fig. 2), at which time a minimum amount of resistance isincluded in circuit.

Assuming attachment of the circuit wires to screws 67 and 63 by means ofnuts 71 and 66, respectively, and further assuming movement of knob 54so that contact member 68 engages the resistance wire 32, continuity ofcircuit may be traced from screw 67 through contact member 68, throughthe resistance wire 32 from the point of contact of said member 68 tothe end 35 of said wire, thence through tubular member 48 to hub member10, to member 13 and portion 56, through metallic Washerf64 and nut 65to screw 63,

and thence to the circuit wire connected to the latter. l

The device illustrated in Figs.' 3, 4 and 5 is in many respectsidentical with thatshown in Figs. 1 and 2, certain changes and additionsbeing incorporated, however, to adapt the same for use as apotentiometer. Thus, Ithe resistance element 29m preferably comprises arelatively wider flexible insulating strip V31 upn which is wound a wire32L which is finer than that employed in the device of Figs. 1 and 2.Moreover said wire is wound more closely adjacent to the ends of theiiexible strip 31* so that the member 68 is in electrical one end of theresistance wire 32 iswound v Yand fastened by solderin as indicated at 76 (Fig. The other en 35 of said wire is connected as described inconnection withi in engagement with said ring Figs. 1 and 2. A screw 77passesthroughthe intermediate insulated o ening 59 in portion 56, saidscrew being in e ectrical engagement with and adapted to support ayoke-shaped contact' element'or brush 7 8, the curved arms 79 and 80 ofthe latter being in alinement with contact ring 74 and provided withsmall bosses or projections 81 and 82 which are held An insulatingwasher 83 rovides for comp ete insulation of screw 77 rom portion 56,Whereas a nut 84 is adapted to hold the screw and its associated partsin position. A nut 85 provides for conneet-ion ci a 'circuit Wire inelectrical engagement with the screvv 77. The device illustrated in Fis. 3 to 5 is otherwise exactlylilre that shown 1n Figs.. i and 2, andfurther description thereof 1s deemed unnecessary,

With each of screws 63, 77 and 67 suitably connected incircuit by meansoi the nuts 66,

y85 and 7l, respectively, continuityof circuit may be traced from thescrevvf(` through contact 68 to a given point in the resistance element,thence in one direction to the lead Wire 35, through member i8, hub 10,member i3 and portion 56 'to screw 63, as set'iorth in connection withFigs. l and 2. An additional circuit is herein provided, 'Which may betraced from. said contact 68 through the remainder of the resistancewire to the ring 7 Li, thence through the brush or contacter 78 to screw77. By the arrangement aforedescribed the Well known potentiometercircuit connections may be'efected.

The manner of assembling the respective devices Will be apparent fromthe foregoing descri tion. It may be further noted, h0wever, t at afterspinning over or riveting the vreduced end i7 of member 48` as indicatedat lines at 86 in said gurc, this feature being omitted from` the otheriigures for clarity of illustration. l l In practice different sizedwires 32 are ernployed` for providing resistance elements of di'erentohmic values, whereas the ohmic value of a particular resistance elementis' preferably markedv upon an uncovered portion of the fiexibleinsulating strip 31 after winding of the resistance Wire. When coatedWire is employed fforthe resistance elements such coating is preferablyremoved from the upper surface o such elements to insure gooddelectrical contact with the member 68.

what I claim andv dem a secure by Lertcrs Patent is: v

l .1. Iin resistance control apparatus, the combination with aA metallichub` member, of a metallicterminal supporting member rigidlfysecuredthereto, a headed member adapted r screw-threaded engagement with saidhuh ber, means at oneend of- .said shaftf for effecting rotationthereof, and means at the other end of said shaft for-positively` engaging. said insulating block.

2. In resistance control apparatus, the combination with ametallic hubmember, of a metallic terminal supporting member rigs idly securedthereto,a headed member adapt-1 ed for screw-threaded engagement withsaid hub member for' attachment of the latter to anl insulating panel orother sup ort, a substantially cylindrical insulatin block rotatablymounted on said hub mem er, an operating shaft axially penetratinglsaidheaded member, means at one end of said shaft for eifecting rotationthereof, means at theV other end of said shaft for positively engaginginsulating bloclr, and a resistance element frictionally secured to saidblock for rotation stantially cylindrical insulating lock rotatl ablymounted on said hub member, an oper atin shaft axially penetratingsaidheaded mem er, ineans at one end of said shaft Jfor effectingrotation thereof` means at the other end of said shaft for positivelyengaging said insulating block, a resistance element )frictionallysecured to said block for rotation therewith, one end of said resistanceelement r, an operating :shaft axlally penetrating said headed membeingelectrically connected with said terminal supporting member through saidshaftV and sal hub member, and a contacter sup! ported by but insulatedfrom said terminal supportn adapted' or sliding engagement with `saielement.

4.1m resistance control apparatus, the combination with a metallic hubmember, of a metallic terminal supporting member rigidly securedthereto, 'a headed member adapted for screw-threaded engagement withsaid hub member for attachment of the latter toy an insulating panell orother support, a substantially cylindrical insulatin block rotatablymounted on said hubmem er, an operating shaft axially penetrating saidheaded mem member, said contactorbein i `stantially cy indricalinsulating in rotation thereof, means at the other end of said shaft forpositively engaging said insulating block, a resistance elementfrictionally secured to said block for rotation therewith, one end ofsaid resistance element being electrically connected with said terminalsupporting member through said shaft and said hub member, a metallicring electrically connected with the other end of said element, and acontact element carried byv but insulated from .said terminal supportingmember for engagement with said ring.

5. In resistance control apparatus, the combination with a metallic hubmember, of a metallic terminal supporting member rigidly securedthereto, a v eaded member adapted for screw-threaded-engagement withsaid hub member for attachment of the latter to an insulatin panel orother suiport, a subock rotatably mounted onsaid hub member, anoperating shaft axially penetrating said headed member, means at one'endof said shaft for eecting'rotation thereof, means at the other -end ofsaid shaft for positively engaging said insulating block, a resistanceelement securedy to said block for rotation therewith, one end of saidresistance element being electrically connected with said terminalsupporting member through said shaft and said hub member, va metallicring electrically connected with the other end of said element, acontact element adapted for engagement with said ring, and a contactoradapted for engagement with said resistance element, said Contactelement andv contactor being respectively supported by but insulatedfrom said terminal supporting member.

6. In resistance control apparatus, the combination with a metallic hubmember, of a metallic terminal supporting member of substantiallyL-shape in cross-section rigidly secured thereto, a' plurality ofbinding posts carried by said supporting member, certain of said bindingposts being insulated therefrom, contactors carried by said last men!tioned binding posts, an insulating block rotatably mounted on said hubmember, a contact ring carried by said block and adapted for engagementwith one 0f said contactors, a resistance element peripherally mountedon said block for rotation'therewith and adapted for engagement with theother of said contactors, said element comprising a flexible insulatingstrip having wire wound thereabout, a metallic link for biasing the endsof said strip toward each other, means for electrically connecting oneend of said wire and said ring, and means for electin i continuity ofcircuit between theother endo said wire and said terminal supportinglmeans, said means comprising an operating shaft in contact with saidwire and said hub member.

7. In resistance control apparatus, the

combination witha metallic hub member, of-

a metallic terminal supporting member of substantially L-shape incross-section rigidly secured thereto, a plurality of binding postscarried by said supporting member, certain of said binding postsbeing-insulated therefrom, contactors carried by said lastmentioned'binding posts, an insulatin block rotatabl mounted on saidhubmem er, a contact ring carried by said block and adapted for engagementwith one of said contactors. a

resistance element peripherally mounted on said block for rotationtherewith and adapted for engagement with the other of said contactors,said element comprising a fiexible insulating strip having wire woundthereabout, a metallic link for biasing the ends of said strip towardeach other, means for electrically connecting one end of said wire andsaid ring, means for effecting continuity of circuit between the otherend of said wire and said terminal supporting means, said meanscomprising an operatin shaft in contact with said wire and said humember, and a disk-shaped member riveted to said shaft,

said member having a plurality of inwardly extending resilientprojections adapted for engagement with co-operative abutments on saidblock for effecting rotation of the latter.

8. In a resistance control device, the combination with a fixed hubmember, of an insulating block rotatably carried thereby, means carriedby said hub member for limiting rotary movement of said block in eachdirection, a rotatable shaft extending through said hub member, andmeans on said shaft adapted to positively engage cooperatin projectionson the rear endof said bloc for effecting rotary movement of the latter.

9. In a resistance control device, the combination with a fixed hubmember, of an insulating block rotatably carried thereby, a rotatableshaft extending through said hub member, and resilient means on saidshaft having radial arms adapted for positive interlocking engagementwith cooperating projections on said block for effecting rotary movementof the latter, said means being also adapted .to effect positiveelectrical engagelient between said shaft and said hub memer. Y

10. In a resistance control device, the combination with a fixed hubmember, of an insulating block rotatabl carried thereby, means carriedby said huh member for limiting rotary movement of said block in eachdirection, a rotatable shaft extending through said hub member, and'means on said shaft adapted to positively engage vsaid block foreiecting rotary movement of the latter, said means comprising adisk-shaped member having a plurality ofradial arms adapted to glligalgecorresponding projections on said 11. In a resistance control device,the combination with a metallic hub member having a metallic terminalsupporting member rigidly secured thereto, of means for rigidly securingsaid hub member to a panel or other support, an insulating blockrotatably mounted on said hub member, means comprising a metallic shaftpenetratingsaid hub member for eiecting rotary movement of said. blockwith respect t0 said hub member, means for limiting such movement of theblock, a resistance element comprising a wire-wound flexible insulatingstrip, a said element being circumferentially arranged on and rictionally secured to said block, one end of said resistance element beingelectrically connected to said shaft, and a contactor adapted to engagesaid element, said contactor being carried by but insulated from saidterminall supporting member.`

12. In a resistance control device, the combination with a metallic hubmember having a metallic terminal supporting member rig idly securedthereto, of means for rigidly securing said hub member to a panel orother support, an insulating blck rotatably mounted on said hub member,means comprising a metallic shaft penetrating said hub member foreffecting rotary movement of said block with respect to said hub member,means for limiting such movement of the block, a resistance elementcomprising a wire-wound flexibletinsulating strip, said element beingcircumferentially arranged on and rictionally secured to 1said block,one end of said resist ance element being electrically connected to Isaid shaft, terminals carried by said terminal supporting member, one ofsaid. terminals,

being in electrical enga ement therewith, an-

other of said terminals eing insulated therefrom, and' a contactorcarried by said last mentioned terminal, said contacter being adaptedfor engagement with said element.

13. In a resistance control device, the combination with a substantiallycylindrical vinsulating block, o'f a resistance element comprising astrip of exible insulating material having a wire 'Qvound thereabout,said element being bent around said block, and means comprising aself-sustaining inwardly bowed resilient metallic member having hookedends penetrating corresponding openings in the ends of said strip tobias'the latter toward each other solely byv the resiliency of saidmember and thereby frictionally holdvsaid element against movementaxially of said block, said member being adaptedl to fit loosely withina notch in said block to prevent relative rotary movement of saidelement .and

said block. i

14. A resistance element comprising a iiexible strip of insulatingmaterial having a resistance wire wound thereabout, said strip beingbent to forma circle'of predetermined

